1. Field
The exemplary embodiment described herein relates to a cleaning apparatus and a cleaning method for the production of semiconductor elements, such as electronic chips, memory elements and the like. According to a further aspect, the exemplary embodiments also relate to an apparatus for storing objects from semiconductor production.
2. Brief Description of Related Developments
Exposure masks (also known as reticles) are used in the fabrication of electronic components, such as for example chips or memory modules, to produce defined structures on substrates of the components by means of photochemical processes. Since these structures include interconnects in the micrometer or even nano range, and even tiny amounts of impurities on the substrate and/or exposure mask leads to scrap, i.e. products which do not satisfy the quality requirements, an extremely high level of cleanness is required. Therefore, components of this type are produced under clean and ultraclean room conditions. To protect the exposure masks from mechanical damage and soiling, they are stored and handled in cassettes or in magazines which are sealed in an airtight manner.
Relatively large particles can easily be detected and removed. The problems are caused by smaller particles, for example with dimensions of 10 μm to 20 μm, which it has hitherto only been possible to remove with a very high level of outlay. For this purpose, cleaning methods have been developed in which a liquid was used to wash the semiconductor production means or the corresponding components or their starting products. On the one hand, these cleaning methods entail a relatively high level of structural outlay in terms of the equipment required to carry them out. On the other hand, the washing liquids used have to be reprocessed or replaced by fresh liquids. Furthermore, the fact that the cleaned objects are wet immediately after the process and therefore have to be dried before they can be reused or processed further may be unsatisfactory.
However, it has been found that, despite these measures, it is not possible to avoid soiling of the exposure masks to a sufficient extent. Moreover, known cleaning apparatus have the drawback of requiring a relatively large footprint in semiconductor factories. This is disadvantageous in particular because relatively expensive installations for producing clean room conditions have to be installed in the factories, and the costs of these installations rise proportionally to the size of the factory.
U.S. Pat. No. 5,967,156 has disclosed a surface treatment apparatus in which different cleaning agents, namely an aerosol and another reagent, are discharged from two nozzles onto a single surface of a substrate, which is disadvantageous in process engineering terms. According to U.S. Pat. No. 5,967,156, the reagent is extracted at a distance from the cleaning point without exploiting any geometry of the suction operation.
U.S. Pat. No. 5,857,474 has disclosed an apparatus and a corresponding method for washing a surface of a semiconductor product with frozen water which is supplied from a water supply nozzle and a gas supply for blowing the ice particles formed off the surface of the semiconductor product, which represents a combination of the drawbacks which have been outlined.
U.S. Pat. No. 6,055,742 has disclosed a reticle cleaning apparatus, in which a gas supply device is provided in the upper region of a cleaning chamber and a gate device and a conveyor device for supplying the reticles are also provided. Since an apparatus of this type—for design reasons since the reticles are secured in the cleaning chamber—can only be used to clean one side of a reticle, this has the drawback of a large footprint if a second cleaning apparatus is to be provided for the second side. The disclosure of an apparatus which is known from JP-A 03 155 550 and in which a surface of a semiconductor product is inspected by blowing off foreign bodies and then observing the effect does not go any further than the content of disclosure of U.S. Pat. No. 6,055,742.
JP-A 04 151 153 has disclosed an apparatus and a corresponding method in which, in a scanning mode, a compressed gas is passed onto a surface of a semiconductor product which is to be checked in order to be able to draw a functional distinction between defects in the semiconductor product and contaminating particles thereon.
JP-A 61 087326 has disclosed a method for cleaning X-ray masks in which an oxygen gas which is supplied is converted into atomic oxygen by a plasma, and in this way organic impurities on the surface of the X-ray masks are cleaned off.
U.S. Pat. No. 4,677,704 has disclosed a system for cleaning a statically charged surface of a semiconductor wafer in which a gas at which vibrations have been produced is passed onto a surface of a wafer, the static charging being kept to a minimum.
JP-A 55 134 851 has disclosed a mask-cleaning apparatus in which a gas which is mixed with ozone is blown at right angles onto a surface of a drying plate, which is held in a drying-plate holder, in order in this way to blow dust off the plate, the dirt-containing gas then being extracted through outlets in the cleaning apparatus.
JP-A 06 168 864 has disclosed a cleaning apparatus in which nitrogen is blown onto a surface of a reticle with the aid of a gas spray, dust being removed from the surface and at the same time being discharged by the nitrogen gas.
U.S. Pat. No. 4,715,392 has disclosed a washing and cleaning device for semiconductor products in which foreign particles are washed off that surface of the semiconductor product which is to be cleaned using a cleaning liquid, after which the semiconductor product is fed to an inspection device for foreign particles and then, if necessary, is returned to the washing and cleaning device.